Summary /

Having an acceptable EC50/TC50 ratio prompted us to investigate these compounds in the T. Cruzi in vivo mouse model. This in vivo model utilizes bioluminescent T. Cruzi, in which the firefly luciferase enzyme is stably expressed within the parasite.xii This method allows for rapid analysis of potential drugs for the treatment of Chagas disease (Figure 2A). The compounds were dosed at 10 mg/kg, once/day (SID) and monitored compared to a control. Treatment began 7 days post infection and the parasite burden was analyzed at day 12 and day 19 (Figure 2B). We found a significant reduction of parasite burden at day 19, compared to the control and after 5 days treatment. These results are significant as other reported in vivo T. Cruzi parasite killing assays were conducted with higher doses (20-100 mg/kg) and more frequent treatment regiments (BID). These results suggest that over a longer treatment time, and using comparable dosing, these compounds would have an even more pronounced effect.

Figure 2. A. Whole-body imaging of mice infected with bioluminescent T. Cruzi parasite, both the control (no treatment) and those treated with benznidazole at 30 mg/kg. B. Ratio of parasite burden after 12 days of treatment for ML217 and analog compound 16. Treatment starts 7 days post infection. Compounds were dosed at 10 mpk SID.

Summary /

ML217 has only limited aqueous solubility (5 μM), and thus could have poor absorption and oral bioavailability. As such, we are encouraged by the improved solubility of subsequent compounds, which have much improved solubility in PBS buffer (pH 7.4) of >150 μM while maintaining comparable potency of ML217. These compounds have not yet been tested in the T. Cruzi assay or the Chagas disease mouse model, but the preliminary results suggest that the solubility liability has already been addressed.